1. No category

Downloaded from orbit.dtu.dk on: Dec 12, 2016
Recycling of
wind turbines
Andersen, Per Dannemand; Bonou, Alexandra; Beauson, Justine; Brøndsted, Povl
Published in:
DTU International Energy Report 2014
Publication date:
2014
Document Version
Publisher's PDF, also known as Version of record
Link to publication
Citation (APA):
Andersen, P. D., Bonou, A., Beauson, J., & Brøndsted, P. (2014). Recycling of
wind turbines. In H. Hvidtfeldt Larsen, & L. Sønderberg Petersen (Eds.), DTU International Energy Report 2014:
Wind energy — drivers and barriers for higher shares of wind in the global power generation mix. (pp. 91-97).
Technical University of Denmark.
General rights
Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners
and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.
• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.
• You may not further distribute the material or use it for any profit-making activity or commercial gain
• You may freely distribute the URL identifying the publication in the public portal ?
If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately
and investigate your claim.
Chapter 13
Recycling of
wind turbines
By Per Dannemand Andersen and Alexandra Bonou, DTU Management Engineering;
Justine Beauson and Povl Brøndsted, DTU Wind Energy
Page 92 — Recycling of wind turbines
→
Wind turbines are one of the most environmentally sound technologies for producing
electricity, and wind energy has very low
environmental impacts. Within the life cycle of a
wind turbine, however, the decommissioning phase
has been identified as a blind spot when analysing
the environmental impacts of wind power. Most
previous impact analyses have focused primarily
on the operational phase of the turbine’s life cycle,
and in some cases also on the manufacturing and
installation phases.
turbines and wind farms will therefore affect decommissioning and recycling 30–40 years in the
future – a rather distant point.
Because the wind turbine industry is relatively
young, there is only a limited amount of practical
experience in the removal and recycling of wind
turbines. This is particularly true of offshore wind
turbines, which are a fairly recent phenomenon.
However, wind turbine recycling is rising up the
agendas of policymakers, researchers and industrialists. Several studies of the environmental impact of
wind turbines have been carried out recently, along
with technology development projects related to
turbine recycling, especially for blades. Some manufacturers have also set targets for the recyclability
of their wind turbines [1].
By the end of 2013 wind power had a total global
installed capacity of 318 GW, a figure that had risen
by approximately 40 GW annually from 2009 to 2013
[3]. Several organisations have developed scenarios
for the future growth of the market. These include the
International Energy Agency (IEA), which has published two such scenarios [4]. In the “2DS” scenario
(an average global temperature rise of 2°C), 1,400 GW
of wind power will be installed by 2030 and 2,300 GW
by 2050. The more ambitious “hiRen” (high renewables) scenario envisages 1,600 GW of wind power
by 2030 and 2,700 GW by 2050. Other organisations
have suggested even higher future market volumes.
The Global Wind Energy Council, the international
trade association for the wind power industry, suggests 2,500 GW of installed wind power by 2030 and
4,800 GW by 2050. These figures do not distinguish
between onshore and offshore sites.
Deployment and decommissioning plans
How big is the problem? How many turbines do we
need to decommission, and when?
The development phase of a new type of wind turbine might take five years. The planning of a large
offshore wind farm might take 5–10 years. Most
wind turbines have a design lifetime of 20–25 years.
The decisions we take today on the design of wind
An older study identified a number of factors affecting the future market volume of wind turbines, and
consequently the total amount of material used and
ultimately to be recycled or disposed of [2]. The same
study also identified factors affecting the design of
future wind technology, and consequently the types
of materials to be used (Table 8).
By 2013 a typical offshore wind turbine had a capacity
of approximately 4 MW and a rotor diameter of 120
m. The sizes of future turbines are more difficult to
predict. The study mentioned above extrapolated
Table 8 – Factors determining the future amounts and types of wind turbine materials
used and ultimately recycled or disposed [2].
Key factors affecting the future market development of wind
turbines – determining the total amount of material used and
ultimately recycled or disposed of:
Factors affecting the design of future wind technology –
determining the types of material used and ultimately recycled
or disposed of:
• National climate and energy policies
• Future power market structures
• R&D expenditure (public and industrial)
• New materials (replacement of steel, new composites, superconducting materials, etc.)
• Design concepts and main components (power electronics, control
strategies, superconducting materials, etc.)
• Grid conditions (grid structure, power quality, etc.)
DTU International Energy Report 2014
Recycling of wind turbines — Page 93
Table 9 – Masses of the major components of a
2 MW turbine [5].
Component
Tower
Nacelle
Mass (tonnes)
143.0
2.3
Hub
13.3
Blades
19.5
Nose cone
0.3
Transformer/converter
5.0
Generator
6.5
Gearbox
16.0
Bed frame
10.5
Main shaft
5.1
to suggest that the most common turbine size in
the period 2020–2030 will be 10 MW [2]. A newer
study has based its conclusion on an existing 2 MW
turbine [5] (Table 9).
The 40 GW of turbines installed annually in the period 2009–2013 will reach the end of their operating
lives during 2029–2033. Anticipating the IEA hiRen
scenario, it is possible to make a rough estimate of
the amount of material that will need to be recycled
in the long term (Table 10). We assume that 1/20 of
the capacity installed by 2030 will need to be decommissioned by 2050; the same estimate for blade
material can be found in a recent German study [6].
By comparison, vehicles reaching the end of their
lives are estimated to reach a mass of 14 million
tonnes per year by 2015 in Europe alone [7].
Future challenges for
decommissioning and recycling
Early life-cycle assessment (LCA) studies of offshore
wind farms have concluded that environmental impacts come from three main sources [8, 9]:
•bulk waste from the tower and foundations
(e.g. from steel production), even though a
high percentage of the steel is recycled;
•hazardous waste from components in the nacelle
(e.g. from alloy steel);
•greenhouse gases (e.g. CO2 from steel manufacturing and solvents from surface coatings).
These results indicated that further analysis should
take into account changes in the materials used in the
tower and the foundations, as well as changes in the
design of components in the nacelle (e.g. direct-drive
designs and greater use of power electronics).
Cables play an important part in recycling plans for
offshore wind farms [8]. Offshore sites require many
kilometres of heavy cables of complex/composite
construction to resist the harsh environment of the
sea. There is a considerable environmental impact
from the manufacture of the cables, and since they
consist of many different materials, cables are also
difficult to dismantle for recycling.
There are some uncertainties and limitations regarding LCA studies of offshore wind turbines. In
particular, the specific processes needed for dismantling and recycling, which are crucial to the
Table 10 – Rough global estimates of recycled masses of key wind turbine components in the future.
40 GW decommissioned annually
by 2029–2033
Steel and cast iron (tower, hub, bed frame, main shaft) – 86t/MW
80 GW decommissioned
annually by 2050
3,440,000 t
6,880,000 t
Alloys (generator, gearbox) – 11t/MW
440,000 t
880,000 t
Blades – 10t/MW
400,000 t
800,000 t
DTU International Energy Report 2014
Page 94 — Recycling of wind turbines
medium
Uncertainty on how to handle
Blades
Nacelle
Dismantling
Organisation
Tower
Hydraulics
Foundation
Gen. and gear
Electro.
and cables
low
Assessment of the
environmental impact and
uncertainties involved in
dismantling, recycling and
disposing of wind turbines
and their components [5]
high
Figure 37 – Assessment of the environmental
impact and uncertainties.
low
medium
high
Importance (damaging effects)
environmental profile, are not known. Many material
recovery processes were not included in these early
analyses. Another example of the limitations of many
environmental impact studies for wind turbines is
that they tend to neglect land use, which is generally
considered a critical point elsewhere. Newer LCA
studies of wind turbines point to two uncertainties
in assessing lifetime environmental impact [10]. The
first relates to what will happen to materials and
components, in particular the blades, at the end
of their lives: will they be recycled, or dumped in
landfills? The second area of uncertainty is about
decisions taken on servicing and maintenance during the operating life of the turbines. Together, these
two uncertainties create an uncertainty of 14–20%
in the predicted life-cycle environmental impact of
wind turbines [10].
while recycling recovers the material value without
concern for the functional value of the component
[5]. However, there exists a second-hand market for
used wind turbines. Turbines considered too old or
too small for mature markets such as Denmark and
Germany can be refurbished and sold in less mature
markets such as Eastern Europe and Latin America,
giving operators practical experience at low cost
[11]. This second-hand market has recently surged.
Another option is to extend the working life of turbines by updating them with newer or refurbished
components. Some independent operators, like the
DMP Group, specialise in refurbished components
for wind turbines. “Repowering” a wind farm usually
implies replacing old turbines with newer and larger
ones. In that sense it is the site that gets repowered
and not the individual turbines.
If old turbines cannot be re-used economically they
must be dismantled, their components recycled
wherever possible, and the remainder dumped or
incinerated. Many components have a commercial
value because they contain materials such as steel
and copper, and most turbine components are well
known to established recycling companies. However,
the consequences of recycling increased numbers of
generators containing rare-earth magnets are not
well studied.
As mentioned above, what happens at the end of
a turbine’s life has a considerable influence on its
overall environmental impact. The options are: second-hand sales of complete turbines; refurbishment
to extend the working lives of turbines in their original settings; remanufacturing and re-use of components; recycling; and landfill.
An older study assessed the environmental impact
and uncertainties related to decommissioning wind
turbines (Figure 37) [2]. The study found that blades
constitute a major problem, and there is much uncertainty about how to get rid of them properly and
safely. The problem lies in the fibreglass composite
used for blades. Fibreglass is a low-value material
and the dust produced when the blades are cut up
creates a hazardous working environment. Empty
nacelles are also hard to recycle because they contain many different types of materials, including
composites and PVC foam. Electronics and cables
are less problematic, since the recycling industry is
used to handling these.
Some studies include only remanufacturing and
recycling. Remanufacturing is the process of returning a used component to its original specifications,
A newer study indicates that dismantling and “reverse
logistics” might be more costly than the original installation phase [5].
DTU International Energy Report 2014
Recycling of wind turbines — Page 95
Based on information from companies the authors
of this chapter have assessed the recycling or disposal rate of wind turbines built using current
technology (Table 11). Electronic components are
notable for their low recycling rate, such that up
to 50% needs to be treated as waste. Since most
LCA and recycling studies of wind turbines focus
on the blades, there seems to be a need for better
knowledge of how to recycle electronics and other
composite components like cables and hydraulic
hoses.
electronic and electrical equipment [7]. Under EPR,
manufacturers are responsible for the life cycle impact of their products [12].
Institutional issues
Who will actually dismantle and remove the turbines
at the end of their lives? Three business models can
be identified. In the first, this is the job of established
independent operators in the removal and recovery
sector. In the second model, which is a variation of
the first, specialist independent operators will carry
out most of the work, but the blade materials will be
recycled by an emerging class of start-up firms set
up to take advantage of this opportunity.
A recent British study of the incentives for recycling composite wind turbine blades in Europe
analysed the legislative regime for the recycling
of blades, and found it to be quite comprehensive.
Blade recycling is subject to EU Directives on issues
such as landfill, vehicles (the End of Life Vehicles
Directive), waste incineration, waste electrical
and electronic equipment (WEEE), and the Waste
Framework [7].
Also important may be the EU rules on extended
producer responsibility (EPR), which has been applied to a number of sectors such as vehicles and
This complexity emphasises the importance of
knowledge exchange and knowledge development in
the interaction between the design, dismantling and
recycling phases for wind turbines. Furthermore, the
institutional and organisational structure required
to dismantle and recycle offshore wind turbines was
until recently quite uncertain [2, 5].
The third model involves collaboration and strategic
alliances between wind turbine producers (Original
Equipment Manufacturers) and the removal and
recovery industry. Of the three, this model is the
Table 11 – Recycling rates and disposal routes for wind turbine components.
Material
Recycling/Disposal rate (%)
Disposal method
Ferrous high alloy
98
Recycling
Ferrous metal
95
Recycling
Steel
Source: Based on authors’
analysis of information
from companies.
Recycling
Aluminium and aluminium alloys
95
Recycling
Copper, magnesium, nickel, zinc and their
alloys
98
Recycling
Precious metals and other non-ferrous metals
and alloys
98
Recycling
Plastics, rubber and other organic materials
100
Incineration with energy recovery
Electronics
50
Recycling with energy recovery
Batteries
100
Recycling
Concrete, bricks etc.
64
Landfill
Sand and gravel
0
Remains in the ground after wind farm is dismantled
Blades
95
Landfill or recycling
Remaining materials
Incineration or landfill
DTU International Energy Report 2014
Page 96 — Recycling of wind turbines
best adapted to the expected regulatory changes
towards extended product liability and increased
producer responsibility. It might also be preferred
by the wind turbine manufacturers (OEMs), since
it will help them to feed knowledge back into their
product development processes and so benefit from
designing for recyclability [5].
However, there seems to be a need to further analyse the societal and environmental consequences
of these business models and perhaps others. In
particular, studies show the need for development
policies to encourage recyclability and to stimulate
markets for second-hand turbines and independent
recycling operators [5].
Recycling fibreglass
As indicated above, it is well known that fibreglass
blades can create recycling problems. Several decades of research have now resulted in practical
methods for recovering and recycling glass fibre
and other materials from composites. [13, 14, 14A]
Unfortunately, high investment and processing costs
mean that the recovered glass fibres are more expensive than pristine ones, so commercial applications
have therefore been limited. The Danish company
ReFiber used pyrolysis to recover glass fibres from
wind turbine blades for re-use in thermal insulation,
but after five years of operation the company ceased
trading in 2007 for economic reasons.
The recovery processes are primarily chemical and
thermal in nature, with processing temperatures
in the range 300–700°C. [15, 16] The most-studied
techniques are the fluidised bed, a thermal oxidation process operating at around 450°C; [17] pyrolysis, which decomposes organic molecules into
smaller ones in an inert atmosphere at temperature
of 300–700°C;[18–21] and supercritical fluids (see
below).[22–24]
Heating glass fibres to temperatures above 250°C
has been shown to degrade their mechanical properties. [14, 23, 25–28] This limits the use of recovered
glass fibres in high-performance composite. One of
the challenges is therefore to reduce the operating
temperature of the recycling processes. Supercritical
fluids are promising in this respect. Many fluids at
DTU International Energy Report 2014
temperatures and pressures just above their critical
points have interesting properties, including high
solvent power and liquid-like density combined with
gas-like diffusivity and viscosity.
The European project EURECOMP (2009–2012) investigated the use of water to dissolve the matrix
material in glass fibre reinforced polyester, but the
results were unpromising at temperatures below
300°C. [22–24]
Another project, Genvind (2012–2016), is now running in Denmark with the aim of finding recycling
and re-use solutions for wind turbine blade materials. Because the reasons for decommissioning blades
are diverse (most often they are still intact), the project is considering several scenarios and process
steps, from dismantling to re-use of complete blades.
The project’s many partners, from both industry
and universities, are working to develop suitable
technologies and future industrial applications.
Another route might be to produce cement by using
decommissioned turbine blades and other waste
composites as both a fuel and a raw material. The
polymer component of the composite acts as a fuel,
while the glass leaves a silica-rich ash that can substitute for some of the sand normally required to make
cement. The Lägerdorf cement plant in Germany,
operated by Holcim, is already doing this, incorporating up to 50% of fibreglass ash into the clinker.
The company claims that the resulting cement is
no different from normal in terms of quality and
applications. [28]
Perspectives
Based on the above, we can make some recommendations for research, industry and policy.
First, there is a general need for more accurate data
to improve LCA calculations relating to wind turbines. This may be especially important for decisions
concerned with service and maintenance. These are
considered key issues in driving down the cost of
electricity produced by wind power, yet they have
environmental consequences that may not yet be
fully understood. Better data is also needed for the
recycling of wind turbine components and materials,
Recycling of wind turbines — Page 97
especially blades. Since materials are responsible for
the largest fraction of the total life-cycle emissions
from wind turbines, uncertainties in data on recycling have a big influence on the LCA of the turbines
as a whole.
Second, design for recyclability is high on the agenda
in many industries, including wind power. However,
there is a need for better understanding of likely
material substitution in future turbine designs. There
may also be a need for more knowledge on how to
dismantle turbines and break down complex components into recyclable materials.
Third, there is a need to know more about the potential markets for products made from recycled
materials. There are established markets for scrap
steel and alloys, but there is limited knowledge about
the market for secondary products from wind turbine recycling, such as composite matrix materials
derived from blades.
Fourth, as wind turbines become more technologically advanced, the use of rare earth materials is
increasing, especially in magnets. We need to know
more about how to recycle or recover magnets and
rare earths.
Fifth, we need policies to stimulate OEMs to design
for recyclability, for example through extended producer responsibility within a product service system
framework. Valuable experience could be learned
from other industries.
Sixth, the current rapid rise in wind power projects in the longer term is creating new business
opportunities for second-hand turbines, refurbished
components, turbine dismantling services, and recycling of materials. Further into the future, policies to
stimulate such markets and entrepreneurial activities
might be needed.
As the global installations of wind turbines increase
to develop issues related to the decommissioning of
wind turbines becomes increasingly higher on the
agenda – both in policy making, among researchers and in industry. This chapter has touched upon
the most important of aspects related to this issue.
However, in a longer perspective much knowledge
is still needed.
DTU International Energy Report 2014